Decimals
NZ Level 5
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Problem solving with decimals (4 ops)
Lesson

Problem solving

When we have a written problem, we need to look for the key words, or clues, to write it as a number problem. We have seen how we can identify our number problem, using multiplication and division with decimals, so now we can look at problems with more than one part.

In Video 1, we look at some of the keywords that might indicate which operation you need to use - multiplication, division, addition or subtraction. We also look at how to calculate the total cost of buying   and one pair of . That means we have to solve two parts of a problem!

Remember!

Make sure you write any units of measurement next to your final answer (e.g. $, kg, m etc).

 

Sharing and deducting

In Video 2 you'll see how we can use division, and then subtraction, to solve a problem. Sophie has spilled some water, so we have to work out what she has left for her hike. We start with a total, then work out individual amounts, once it's been shared. Finally, we subtract the amount that has been lost, to see what Sophie ends up with. 

Remember!

Don't forget to follow the  order of operations when you're solving number problems.

 

Worked examples

Question 1

Adam was buying supplies for the new school year. He bought $5$5 books at $\$14.82$$14.82 each and a pencil case for $\$6.36$$6.36. How much did he spend in total?

Question 2

Paul has a part-time job on the weekend delivering newspapers. He is paid $\$14.29$$14.29 an hour, but his little sister helps and so he gives her the money earned for one hour. If Paul works for $7$7 hours in total, how much money does he earn for himself?

Question 3

Carl trains $6$6 days a week. On weekdays he runs $3.4$3.4 km, and on Sunday he runs $4.6$4.6 km. How far does he run in a whole week?

Outcomes

NA5-3

Understand operations on fractions, decimals, percentages, and integers

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